Chagrin:
Also http://ruggedcircuits.com/gerbmerge/Python script for panelizing. My python-foo is a little weak and I couldn't get it running on my Linux system however; YMMV.
JoeN: If you want to do home etching you just need a program that will print an image of the top or bottom layers (bmp, png, etc.). You don't want Gerber format. Eagle handles that just fine and I'm sure KiCAD does as well.
I understand all you have to do is make a mask to do it at home (you can do this with a pen or tape). But I would think you would want to do the work in a program that exports to Gerber in case you ever want to move the work to manufacturing. Anyway, any comments on KiCAD?